DENIERS SAY:

The same scientists that raise the alarm about global warming were predicting an ice age more than 30 years ago.

SCIENCE SAYS:

The climate crisis is happening now. An ice age may or may not happen in thousands of years.

The scientific evidence is clear: Climate change is happening now and human beings are to blame. In the 1960s and 70s, scientists knew that human activities were changing the Earth’s climate. But which factors would have a bigger effect? Global warming pollution, like carbon dioxide? Or pollution with a cooling effect, like the particles that make up haze? And would human activities override the natural factors that affect our planet’s climate? By the end of the 1970s, most scientists were coming to the conclusion that the world would indeed warm because of carbon pollution. This consensus grew even stronger over time: Today, 97% of climate scientists with Ph.D.s who are actively publishing in their field agree that humans are warming our climate.

Additional info from Skeptical Science

In the 30 years leading up to the 1970s, available temperature recordings suggested that there was a cooling trend. As a result, some scientists suggested that the current interglacial period could rapidly draw to a close, which might result in the Earth plunging into a new ice age over the next few centuries. This idea could have been reinforced by the knowledge that the smog that climatologists call "aerosols" — emitted by human activities into the atmosphere — also caused cooling. In fact, as temperature recording has improved in coverage, it’s become apparent that the cooling trend was most pronounced in northern land areas and that global temperature trends were in fact relatively steady during the period prior to 1970.

At the same time as some scientists were suggesting we might be facing another ice age, a greater number published contradicting studies. Their papers showed that the growing amount of greenhouse gases that humans were putting into the atmosphere would cause much greater warming — warming that would have a much greater influence on global temperature than any possible natural or human-caused cooling effects.

By 1980 the predictions about ice ages had ceased, due to the overwhelming evidence contained in an increasing number of reports that warned of global warming. Unfortunately, the small number of predictions of an ice age appeared to be much more interesting than those of global warming, so it was those sensational "ice age" stories in the press that so many people tend to remember.

The fact is that around 1970 there were six times as many scientists predicting a warming rather than a cooling planet. Today, with 30+ years more data to analyze, we've reached a clear scientific consensus: 97% of the top climate scientists agree with the view that human beings are causing global warming.